Agricultural waste extensive mechanical pretreatment at lab

R. Bayard, Helen Coarita Fernandez, P. Buffière

Corresponding author: [email protected]

THESSALONIKI 2021

Agricultural waste extensive mechanical pretreatment at lab-scale before anaerobic digestion: An integral approach

Laboratoire DEEP, Université de Lyon, INSA Lyon - France

8th International Conference on Sustainable Solid Waste Management, Thessaloniki, 23–26 June 2021

mailto:[email protected]

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ResultsMaterials and methodsObjective ConclusionsIntroduction

→ Eliminate unwanted elements→ Increase biodegradability &

bioconversion rate→ Improve the homogenization→ Guarantee the balance of the ration→ Improve rheological properties→ Reduce operation and maintenance

costs (OPEX)

Why to use a pretreatment?

Photo : Pacaud, S., Experimental Farm La Bouzule.

Anaerobic digestion / lignocellulosic biomass feedstocks : Challenges Clogging of valves, pipes and pumps Mixing problems Low or slow bioconversion to methane

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Mechanical pretreatments


In the agricultural sector, mechanical pretreatments are the most applied operations. There is a wide range of mechanical technologies (ball mills, disc mills, chain mills, etc.), the hammer and knife mill being the most used.

- Easy to use,- No risk of inhibitors production and,- Do not require the use of costly operations like rising the temperature or adding chemicals

Knife millsChain millsHammer mills

*Disponible sur: https://www.verde-energy.fr/bio-preparateur-tqz/

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But…

Evaluate the physical and biochemicaleffects using successive mechanicalpretreatments on different biomassfeedstock at in situ & lab-scale


Mechanicalpretreatment

The evaluation of the efficiency of a mechanical pretreatment is adifficult task.

To our knowledge, there are still very few objective criteriaenabling to qualify separately the different effects of mechanicalpretreatments. Indeed, mechanical operations are a combinationof size reduction, mixing and fiber breakdown.


1- Selection of several sites with specific mechanical pretreatments / biomass

Site #3Site #2Site #1

Mobile Hammer Mill (HM1) Cattle Manure

Hammer mill (HM2) Cattle Manure

Chain Mill (CM) Cattle Manure + silage

Pretreatment types

Feedback Biomass Availalability

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2- Biomass sampling before and after mechanical operation


3- Lab-scale experiments to define functions & to compare with full-scale mechanical pretreatments

Mixing

Blending

Shredding Size reduction

Homogenization

Fibres destructuration

Low speed shreddingmachine BLIK

Householdkneadingmachine

Laboratoryblender

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3- Lab-scale experiments : main effects

BioMethane Potential (BMP) OM solubilisation : Chemical

Oxygen Demand (COD), (BMP of liquid fraction), nitrogencontents, VFA…

Mechanical pretreatments evaluation effects

Physical properties

Biochemicalproperties

Particle size distribution Water Retention Capacity Rheological properties

Biomass characterization : The procedure was based on leaching procedure (water extraction) of the raw sample, which enabled the measurement of the contributions of water-soluble and particulate phases of biomass dedicated to anaerobic digestion

Leaching procedure: 10:1 water/TS ratio during 2 h under constant flip-flop rotation (10 rpm)

Teixeira Franco, R., Coarita, H., Bayard, R., & Buffière, P. (2019). An improvedprocedure to assess the organic biodegradability and the biomethane potentialof organic wastes for anaerobic digestion. Waste Management & Research, 37(7), 746–754.

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Shredding

Lab-scale experiments : main effects

Indicators Effects

Particle size distribution +++ (↘ coarse particles)

Water retention capacity +

Rheological properties(Apparent viscosity, yieldstress)

+++Until 50% of yield stress

reductionReduction of the apparent

viscosity

Solubilisation ++

BioMethane Potential (BMP) +/- [+ 0-3%]

Kinetic constant (k) + [+ 0-85%]

Figure 1. Particle size distribution, substrate: SilageST: No treatment, B: Shredding, BM: Shredding+ Mixing, BMMI: Shredding + Mixing+ Blending


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Shredding


Indicators Effects

Particle size distribution +++ (↘ coarse particles)



+++Until 50% of yield stress


viscosity

Solubilisation ++



Figure 2. Apparent viscosity, substrate: cattlemanure+ silage. ST: No treatment to 8%TS, B: Shredding to 10%TS

Abrams cone V-funnel


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Shredding+ Mixing


Indicators Effects

Particle size distribution -/+

Water retention capacity +++


++Until 30% of yield stress


viscosity

Solubilisation +



Figure 3. Water retention capacity, substrate: SilageST: No treatment, B: Shredding, BM: Shredding+

Mixing, BMMI: Shredding + Mixing+ Blending


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Shredding+ Mixing + Blending


Indicators Effects

Particle size distribution + (small size particles reduction)



++

Solubilisation +++

BioMethane Potential (BMP) ++[+ 0-21%]

Kinetic constant (k) ++ [+ 17-90%]

Figure 4. COD distribution. Substrate: Cattlemanure. ST: No treatment, B: Shredding, BM: Shredding+ Mixing, BMMI: Shredding + Mixing+ Blending


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Shredding+ Mixing + Blending


Indicators Effects

Particle size distribution + (small size particles reduction)



++

Solubilisation +++

BioMethane Potential (BMP) ++[+ 0-21%]

Kinetic constant (k) ++ [+ 17-90%]

Figure 8. BMP and soluble BMP contrinution, substrate: Silage ST: No treatment, B: Shredding,

BM: Shredding+ Mixing, BMMI: Shredding + Mixing+ Blending


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Size reduction

Matterhomogenization

FibersdestructurationBlending

Shredding

Mixing

Physical properties

improvement

Bioconversion improvement

(BMP ↗)

BMP rate improvement (k ↗)

Lab-scale experiments to define functions and effects

Full-scale pretreatment / lab-scale – statistical analysis (PCA)


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Correlation Function identification

k



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Shredding

k



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Shredding & Mixing

k



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Shredding+ mixing + blending

k



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Shredding + mixing + blending

Chain Mill (CM)

Shredding+ mixing

Hammer Mill (HM1)

ShreddingMobile

Hammer Mill (HM1)

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Improve the physical methodscharacterization

Outlooks

Further investigations …

Improve the comprehension about linked physicalmechanisms to methane bioconversion

Deeper organic mattercharacterization

Free and Bound water determination

ResultsMaterials and methodsObjective OutlooksIntroduction

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ευχαριστώ! [email protected]

This research program was funded by

8th International Conference on Sustainable Solid Waste Management, Thessaloniki,23–26 June 2021


https://thessaloniki2021.uest.gr

… with the funding of a doctoral scholarship by the Bolivian Ministry of National Education

https://thessaloniki2021.uest.gr/

Agricultural waste extensive mechanical pretreatment at lab

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